| random numbers in version 4.0 [message #10398] |
Tue, 25 November 1997 00:00 |
Kirt Schaper
Messages: 6
Registered: February 1997
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Junior Member |
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Has anyone else encountered odd behavior with random numbers in
IDL version 4.0? Specifically, if you repeatedly generate an odd
number of random numbers with the same seed, you don't get the same
numbers (strictly speaking, you do get the same numbers, but shifted
one position). For example:
% idl
IDL. Version 4.0.1 (sunos sparc).
Copyright 1989-1995, Research Systems, Inc.
All rights reserved. Unauthorized reproduction prohibited.
Installation number: XXXXXXX.
Licensed for use by: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Initial setup: quiet=1, order=0
IDL> seed = 10.
IDL> s = seed & print,randomn(s,3)
2.10917 1.36675 -1.02318
IDL> s = seed & print,randomn(s,3)
-0.568035 2.10917 1.36675
IDL> s = seed & print,randomn(s,3)
2.10917 1.36675 -1.02318
IDL> s = seed & print,randomn(s,3)
-0.568035 2.10917 1.36675
This behavior has been repeated on HPUX, Digital UNIX and Solaris
version of IDL. It seems to have gone away in version 5 but we
are stuck with version 4.0 until the convolv 2X slowdown in
version 5 is fixed.
kt
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